This invention relates to electrical conductor wire tracing systems. In particular, this invention is concerned with the tracing of a composite reference signal along an electrical conductor wire and, by so doing, detect and accurately locate any existence of soft faults, such as frays, in the electrical conductor wire.
The NASA Wiring Working Group was initiated in to address the problem of wiring systems integrity and, in particular, the wire integrity problem as related to aged wiring systems. The NSTC Committee On Technology, Wire Systems Safety Interagency Working Group, consisting of NASA, F.A.A and the D.O.D., presented a Review of Federal Programs for Wire System Safety, dated November 2000. This Review acknowledged the fact that the wiring system problem extended far beyond the aviation industry and, in fact was a major concern throughout our society.
According to Eric van Doorn, Ph.D. and Devendra Tolani, Ph.D. of Intelligent Automation Inc., as stated in their paper entitled Radical Extension Of Time Domain Reflectometry For Detection And Location Of Flaws In Aircraft Wiring Systems, 2005, “However, there are currently no methods available that can reliably detect and localize soft faults, such as insulation damage, or frays.”
Wire and cable tracers trace the presence of a reference signal along an electrical conductor wire in order to detect and locate opens and/or shorts in the conductor wire. Many wire tracers employ a variety of different frequency generation, modulation and transmission schemes to provide a traceable reference signal. The modulation schemes employed in these prior arts usually entail the modulation of a high frequency, usually in the upper audio range, by a lower modulating frequency. U.S. Pat. No. 3,991,363 makes use of such a modulation scheme by modulating a high frequency (100 KHz.) and a low frequency (11 Hz.) and transmitting the composite of these frequencies so as to have the higher frequency appear as a pulsed signal along the conductor cable and thus provide a traceable reference signal. U.S. Pat. No. 4,896,117 describes the benefits and drawbacks of transmitting and detecting such high and low frequency signals along a conductor cable. Prior art wire tracers can trace a composite reference signal along the conductor wire when the conductor wire is behind an interior wall or in a bundle of other conductor wires. The problem with these wire tracers is the lack of effectiveness when the conductor is enclosed in a denser material such as metal. One main problem with these prior art devices is the lack of sufficient sensitivity to receive the injected reference signal and thus precisely detect and locate a hard fault or a soft fault, such as frayed wires, in a conductor wire.
The current state of technology employed to address the problems associated with the detection and locating of hard and soft faults in electrical conductor wire include Time Domain Reflectometry, Frequency Domain Reflectometry and Standing Wave Reflectometry. TDR, one of the most widely used method, lacks the sensitivity to reliably and accurately locate soft faults. TDR, FDR and SWReflectometry testing equipment is expensive, bulky, requires a highly trained technician to perform the testing and is less than 100% effective in detecting and locating faults in conductor wire integrity. Furthermore, these Reflectometry technologies require a known baseline measurement, of the conductor to be tested, for the results to be accurate. Having the conductor's baseline measurement allows some of the TDR devices to be able to locate a hard fault in an electrical conductor's integrity to only within six inches of the actual hard fault.
Recognizing that prior arts, employing composite reference signal tracing, exist and also recognizing that prior arts in the detection and location of wiring faults exist, it is the aim of this invention to improve on such conductor wire tracing systems by utilizing the nonlinear tuned receiver antenna circuit to reliably detect and accurately locate a soft fault in an electrical conductor wiring systems. Emanuel Gluskin, in his paper, A Nonlinear Resistor And Nonlinear Inductor Using A Nonlinear Capacitor, dated July 1998, made mention of obtaining a nonlinear inductor through the use of a nonlinear capacitor. “It is noted, and considered with some details, that the use of such a capacitor in a simple switched-capacitive circuit which imitates a resistance enables a nonlinear frequency-controllable resistance to be obtained, and that the use of such a capacitor as a load for a gyrator circuit enables a nonlinear inductor to be obtained.” Utilizing this invention's nonlinear tuned receiver antenna circuit significantly increases the reception of the generated reference signal and by so doing, provides a low cost, hand held tracing and fault location system solution to the current lack of methods to reliably detect and accurately locate a soft fault in an electrical conductor wire.